RKI Instruments 35-3010RK-06-02 - Manual (Page 24)

20 • 35-3010RK-06-02 Sample-Draw Detector
Calibration, CO
2
Detector
This section describes how to calibrate the CO
2
sensor in the sample-draw detector. It
includes procedures to set the zero reading, set the response reading, and return to normal
operation.
NOTE: This procedure describes calibration using a demand flow regulator, a CO
2
calibration cylinder, and a 3-gas calibration cylinder.
Setting the Zero Reading
CAUTION: This procedure may cause alarms at the monitoring device. Take appropriate action
to avoid this, such as entering the calibration mode at the monitoring device.
Since there is a background of CO
2
in air of typically 200 to 400 ppm, it is necessary to use
a cylinder that is free of CO
2
, such as a 3-gas mix or a 100% nitrogen cylinder, to set the
zero signal of the CO
2
detector. Fresh air cannot be used. The calibration kit for this
sample draw detector includes a 3-gas mix that can be used to set the zero reading.
1. Open the housing door.
2. Screw the regulator into the 3-gas mix or 100% nitrogen cylinder.
3. Connect the calibration kit sample tubing to the regulator.
4. The zero (fresh air) reading for the CO
2
channel is set at the controller. See the
controller operator’s manual for instructions to set the zero reading.
5. When the instructions call for applying gas to the detector, connect the sample tubing
from the regulator to the inlet line at or near the INLET fitting.
6. Allow the gas to flow for one minute.
7. Set the zero (fresh air) reading according to the controller operator’s manual.
8. Disconnect the sample tubing from the inlet line.
9. Unscrew the regulator from the 3-gas mix. Leave the sample tubing connected to the
regulator.
Setting the Response (Span) Reading
1. Screw the regulator into the CO
2
calibration cylinder.
2. Connect the calibration kit sample tubing to the regulator.
3. Follow the directions in the controller’s operator’s manual for setting the response
reading for the CO
2
channel.
4. When the instructions call for applying gas to the detector, connect the sample tubing
from the regulator to the inlet line at or near the INLET fitting.
5. Allow the gas to flow for one minute.
6. Set the response (span) reading according to the controller operator’s manual to
match the calibration gas concentration.
7. Disconnect the sample tubing from the inlet line.
8. Unscrew the regulator from the calibration cylinder.